Field of the Invention
The present invention relates to a mobile X-ray imaging apparatus for an X-ray imaging relative to a subject, and particularly relates to a mobile X-ray apparatus operable under a normal drive and operable along with a fine movement operation.
Description of the Related Art
In a medical practice, an X-ray imaging must be conducted in some cases by going around the patient who cannot be moved to the imaging room. In addition, an emergency X-ray imaging must be conducted in a surgical operation room in some cases. In such cases, as an apparatus for the X-ray imaging of the patient, a mobile X-ray imaging apparatus movable inside the hospital has been applied (e.g., Patent Document 1.)
Referring to FIG. 10, the inventor illustrates the structure of a conventional mobile X-ray imaging apparatus. Relative to the conventional example, a mobile X-ray imaging apparatus 101 comprises a base unit 103, a drive wheel 105, a front wheel 107, a mast 109, a boom 111, an X-ray tube 113 and a drive handle 115.
A pair of drive wheels 105 is mounted to the right-and-left side of the rear-bottom part of the base unit 103. The base unit 103 moves forward-and-backward following the rotation of the drive wheels 105 and turns to right-and-left depending on the difference of rotation rates between the right drive wheel 105 and the left drive wheel 105. The drive wheels 105 having an unturnable structure are configured rotatable by the electric motor installed inside the base unit 103. The front wheels 107 are mounted to the right-and-left side of the front-bottom of the base unit 103 and freely turnable depending on the turn direction of the base unit 103.
The mast 109 is mounted in the standing position at the front part of the base unit 103 and rotatable around the perpendicular axis. The one end of the boom 111 is connected to the mast 109. The boom is movable in the horizontal direction and the X-ray tube 113 is mounted to the other end, and a plurality of pressure sensors is installed inside the drive handle 115. The pressure sensors detect the pressure added to the driver handle 115 by the operator and the rotation of the drive wheels 105 is controlled based on the detected pressure.
When the mobile X-ray imaging apparatus 101 is applied, the operator moves to the patient room, where the X-ray imaging subject is present, along with the mobile X-ray imaging apparatus 101 while operating the drive handle 115. When moved in the patient room, referring to FIG. 11, the mast 109 and the boom 111 are appropriately moved to the optimal position to move the X-ray tube 113 for the X-ray imaging. And then, the X-ray is irradiated from the X-ray tube 113 to the subject M to take an X-ray image.
However, the X-ray tube 113 is supported by the base unit 103 through the mast 109 and the boom 111 so that the movable range of the X-ray tube 113 is limited relative to the base unit 103. Accordingly, when an appropriate imaging position relative to the subject is not in the movable range of the X-ray tube 113, the base unit 103 must be moved in an infinitesimal distance to perform fine adjustment of the position of the mobile X-ray imaging apparatus 101. In such case, if the base unit 103 is moved using the drive handle 115, the movement rate of the base unit 103 is high so that the fine adjustment of the position of the mobile X-ray imaging apparatus can be arduous. Accordingly, the move of the X-ray tube 113 to the appropriate imaging position can become problematic.
Accordingly and recently, referring to FIG. 10, a structure further including a fine movement switch 117 other than the drive handle 115 to perform a fine operation as to the base unit 103 is disclosed (e. g., Patent Document 2, 3.) When an operator operates the fine movement switch 117, the drive wheel 105 rotates a lower rate than in the case of the operation of the drive handle 115. The base unit 103 moves slightly in a low speed to forward or backward according to the rotation of the drive wheels 105 so that the fine adjustment of the position of the mobile X-ray imaging apparatus 101 can be performed. Hereinafter, the case when the drive wheels 105 are controlled by the operation of the drive handle 115 is described as “drive mode”, and the case when the drive wheels 105 are controlled by the operation of the fine movement switch 117, which is described as “fine movement mode.”